Container Closure With Tamper Evidence

ABSTRACT

A closure ( 2 ) for a container body ( 4 ) comprises a base ( 6 ) with a hinged lid ( 8 ). The base has a depending skirt ( 10 ) and a flange ( 12 ). The horizontal flange ( 12 ) of the base is sealed to a rim of the container body by means of an induction heat sealed foil ( 14 ). The side wall of the container body is stepped inwardly and the skirt is deep and thin-walled and is provided with at least one weakened region to define a fracture point. Any leverage of the skirt will at least leave a mark and is liable to tear the skirt at the fracture point. Preferably the weakened regions are reduced wall section ribs are moulded into an interior face of the skirt at vulnerable areas such as the corners and centres of the side walls to provide additional tamper evidence.

TECHNICAL FIELD

The present invention relates to container closures and more specifically to a package where the container closure can be applied to a container body so that it cannot be removed without leaving evidence that the package has been tampered with.

Those with malicious intent may wish to contaminate the contents of a filled and un-opened container. The refilling of genuine containers also represents a serious risk to consumers and brand owners. While it is desirable that closures should be readily applied to the container body during the manufacturing process and also be separable for recycling and waste disposal purposes, the prevention of counterfeiting and contamination requires either that the separation be evident or result in such destruction of the closure and/or container body that it cannot be re-used.

The present invention particular relates to large containers such as used for baby milk powder as described in WO 2011/067585 A (BAPCO CLOSURES RESEARCH LTD) 9 Jun. 2011. This type of package comprises a container body and a closure, the closure being a base with a lid adapted to close over the base, the base comprising a horizontal flange surrounded by a depending skirt, the base defining an opening adapted to fit over an open mouth of the container body; the container body having a side wall which terminates in a rim of the open mouth of the container body; and an induction heat sealing foil adapted to be secured to the rim of the container body and the base.

The base in the context of such a closure is sometimes referred to as a spout particularly in relation to smaller containers where the base defines the pouring spout for delivering the contents from the container.

The use of the BAP (Registered Trademark) technology as described in WO 99/61337 A (SPRECKELSEN MCGEOUGH LTD) 12 Feb. 1999 whereby an induction heat sealed foil is bonded to both the container body and the closure and is removable by tearing out rather than peeling away, provides some intrinsic tamper evidence. That patent also describes and claims the use of a weakened recess in an upper surface of the horizontal flange of the base around the opening which causes a skirt of the base to separate if an attempt is made to lever off the base.

Typically a skirt of such a closure will be made with a projecting rib that engages with an overhanging recess around a neck of the container body so that the two parts latch together. This necessarily requires the skirt to flex as it is pushed on to the container body. This limits how thin it can be if it is not to be damaged during installation. However no such mechanical engagement is required when an induction heat sealing foil provides the primary seal between the container body and the base.

It is standard practice when creating a neck formation on a container body to provide some sort of lateral projection, whether this is intended to act as a carriage ring for transporting the container body or as an engagement mechanism for a threaded base. Therefore, there is some sort of overhang over which a base can be latched. This facilitates the placement of a replacement base.

DISCLOSURE OF INVENTION

The present invention provides a package comprising a container body and a closure, the closure being a base with a lid adapted to close over the base, the base comprising a horizontal flange surrounded by a depending skirt, the base defining an opening adapted to fit over an open mouth of the container body;

-   the container body having a side wall which terminates in a rim of     an open mouth of the container body; and -   an induction heat sealing foil adapted to be secured to the rim of     the container body and the base; -   characterised in that the side wall of the container body is stepped     inwardly to provide a first step adjacent a terminal edge of the     skirt; and in that the skirt is a non-structural thin wall having at     least one weakened region to define a fracture point if the skirt is     subjected to lateral movement away from the container body.

In this package, the skirt is present purely to cover an inwardly stepped region of the side wall of the container and does not need to perform any latching engagement with the container body. It can be made relatively deep so that in combination with its reduced thickness, the leverage needed to lift it away from the container body will at least leave a mark and is liable to tear the skirt at the fracture point. Preferably the weakened regions are reduced wall section ribs that are moulded into an interior face of the skirt at vulnerable areas such as the corners and centres of the side walls to provide additional tamper evidence.

The use of a relatively deep skirt allows the closure to be positioned reliably on the container body during production prior to sealing without the need for any mechanical latching to prevent premature dislodgement.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be well understood, an embodiment thereof will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 is a perspective view of the package with the closure attached to the container body with the lid in an open position

FIG. 2 is a perspective view of the container body;

FIG. 3 is a perspective view looking into an interior of the base of the closure;

FIG. 4 is a section through the skirt of the base taken on the line A-A in FIG. 1; and

FIG. 5 is a horizontal section through the skirt of the base taken at one corner.

MODE(S) FOR CARRYING OUT THE INVENTION

A package is created from a closure 2 which is fitted to an open top of a container body 4 as shown in FIG. 1. The closure comprises a base 6 connected to a hinged lid 8. The base has a depending skirt 10, which overlies a neck formation of the container body 4, and a flat horizontal flange 12, which sits on top of a rim of the container body and defines an opening for access to the contents of the container body.

The closure is sealed to the rim of the container body by means of an induction heat sealing foil 14 which has a coating of a compatible plastics material adhered to each surface of the foil so that it can be welded both to a rim of the container body and to the base of the closure in the manner described in EP 1656306 A (BAPCO CLOSURES RESEARCH LTD) 17 May 2006.

A removable part 16 surrounds the opening and is connected to the horizontal flange 12 by means of a frangible region 18. The removable part is also sealed to the induction heat sealing foil 14. A ring pull 20 raised above the surface of the foil is provided to enable the consumer to remove the removable part.

The skirt 10 is thin-walled and terminates in a plain edge 22 without any inwardly projecting parts so that any leverage of the skirt will at least leave a mark and is liable to tear the skirt. Each of the corners 24 of the skirt is moulded so that the wall section is reduced in this area. Ribs 26 with an even further reduced wall section are moulded into these corners. Preferably, an outer surface of the corner is smooth so that the vulnerability of the corner is not exposed to the user. Other reduced wall section areas 28 may be provided in the centres of the side walls of the skirt. These are formed as pairs of ribs. A formation 30 to engage with a latch 32 on the lid 8 is provided at a central position in the front side wall of the skirt.

The skirt 10 is preferably made from polypropylene which has a low yield point so that at relatively low stress the skirt will begin to deform plastically and will not return to its original shape, thereby providing clear evidence that the pack has been tampered with. The skirt is relatively deep, preferably 8 mm or more but subject to cost issues could be as deep as 20 mm. However moulding constraints for the specific plastic used, which must be able to flow into all parts of the mould within a reasonable timescale, may limit the depth as may the need to be able to remove the moulded part undamaged from the mould.

The skirt may have a maximum thickness of 0.8 mm, preferably less than 0.5 mm and the reduced wall sections may be 0.2 mm thick reducing to 0.1 mm at a rib 26, 28. Polypropylene is very vulnerable to stress cracking and when coloured material is stretched past its yield point, it will show permanent white marking. Polypropylene has a yield strength of 12-43 MPa and for this application a material with a yield strength in the range 12-20 MPa is preferable. A chalk filled polypropylene could be used to provide a relatively brittle skirt. However, the ring pull and removable part should not be unduly brittle if they are to function correctly. It will be appreciated that co-injection could be used in order to mould the skirt from a different material from the remainder of the closure in order to benefit from the most appropriate properties of the plastic used in the various parts of the component.

If an attempt is made to lever off the skirt by prying under the edge with any sort of sharp instrument, the thin wall section will retain the deflection and discolouration will appear. If too much force is applied on the thin wall sections then they will readily split either side of the instrument and peal upwards. The splitting ends of the thin wall sections prevent removal and destroy the closure so that it cannot be reused. If the prying attempt is made at the corners then the further vulnerability here created by the reduced section ribs 26 means that the skirt will even more readily split and peal upwards. The ultra-thin ribs act as bridges that facilitate a crisp tear of the wall. The reduced thickness regions 28 in the centres of the side walls target what might be considered to be the easiest portion to lift off without demonstrating damage.

All of the thickness reduction is provided by moulding the interior surface of the skirt 10 as can be seen in FIG. 3. The necessary ridges and ribs can be formed in a steel face of a mould core used to create the closure. The relative dimensions of the parts of the skirt will be determined by the density and melt flow index (MFI) of the plastic used to mould the component. Using a lower density plastic with a high MFI will allow the finest details to be formed as the plastic will be able to flow through the narrow gaps between the mould cores. The risk of damage to the thinnest portions when the mould core is removed probably places a limit of about 0.4 mm on the overall thickness of the skirt, though this may be reduced with newer plastics and moulding techniques. An external surface of the skirt is completely smooth except for the latch and terminates in a fine thin edge which falls adjacent the step 44 so that the outer wall surface of the skirt 10 merges smoothly and continuously with the main body of the container leaving only the most minimal space between body and closure. The depth of the latch only needs to be at about 5 mm deep and therefore the external surface of the skirt can be entirely smooth below that level. Keeping the external lines of the package smooth makes it even more difficult to find an entry point into which to introduce a tool to lever off the closure.

A trough 34 of reduced wall section is also formed in the horizontal flange of the base to enable the skirt to be snapped away from the remainder of the base if a lever is applied under the skirt. This trough 34 acts as a hinge mechanism so that any levering force applied to the skirt results in the destruction of the skirt and leaves the base still attached to the rim of the container body.

The skirt is relatively deep, preferably 8 or 15 to 20 mm. Because the skirt has no structural role to play in sealing the package or supporting the contents, it can be made deeper than a conventional closure. In a package such as described, the skirt can come down close to the point in the package where indentations are provided to allow the container body to be gripped. The longer/deeper the skirt, the easier it is to ensure that the skirt will fracture and break either at the ribs or trough 34 because the lever length increases with the depth of the skirt. The depth of the skirt also gives an impression of overall solidity to the consumer.

The base 12 includes an area 36 in one corner that carries formations 38 designed to receive and hold a utensil 40 for storage after it has been detached from the removable part 16.

Other features of the base which enable it to be sealed together with the lid are as previously described in WO 99/61337 A (SPRECKELSEN MCGEOUGH LTD) 2 Dec. 1999 and other prior art patent applications from Bapco Closures Research Ltd, which are incorporated herein by reference.

The container body 4 has a recessed neck formation 42 which provides a horizontal ledge 44 around the container body 4 at which a lower edge of the skirt of the base will terminate to provide a smooth and continuous outer surface for the package. An upper edge of the neck formation defines an in-turned rim 46 which is induction heat sealed to the foil 14 as shown in FIG. 4. A warning message can be embossed or printed on the recessed vertical wall of the neck formation so that, if this is visible to the consumer, they will know the pack is not as manufactured and is likely to have been tampered with. The neck formation is stepped further back at a second step 48. The step is preferably inclined to facilitate moulding. This provides additional space inside the base of the closure adjacent the mouth of the container body to receive the formation 30 which projects inwardly from an interior surface of the skirt. This creates a further step 48 in the neck formation but there is no overhang which could be used to latch with a replacement base. Both recessed vertical portions 50, 52 of the neck formation which are hidden in use by the closure can bear warning messages.

Preferably the neck formation is, apart from any recessed or embossed writing, a smooth vertical wall and does not provide any continuous recesses around the body which could be used to engage with a replacement closure that is held in position by mechanical means rather than the foil sealing.

The container body can be filled right up to the rim 46 as it is sealed by the sealing foil 14. Therefore, the depth of the closure has no impact on the capacity of the package.

The relative dimensions of the thin wall of the skirt and its depth will of course need to be selected in dependence on the overall dimensions of the package.

Reference to a skirt which has no inwardly projecting parts is intended to refer to parts which project inwardly of a profile defined by the thickest part of the skirt wall section. It will be appreciated that where reduced wall sections to improve the vulnerability of the skirt to plastic deformation, tearing or peeling are present but do not extend the full vertical height of the skirt, the lower edge may be thicker than these reduced wall sections. However, such a ridge 60 as appears in the corners does not project inwardly of the overall profile of the skirt. It may also be necessary to produce an indented formation 30 above the edge of the skirt to provide for engagement with a latch 32. 

1. A package comprising a container body and a closure, the closure being a base with a lid adapted to close over the base, the base comprising a horizontal flange surrounded by a depending skirt, the base defining an opening adapted to fit over an open mouth of the container body; the container body having a side wall which terminates in a rim of an open mouth of the container body; and an induction heat sealing foil adapted to be secured to the rim of the container body and the base; characterised in that the side wall of the container body is stepped inwardly to provide a first step adjacent a terminal edge of the skirt; and in that the skirt is a non- structural thin wall having at least one weakened region to define a fracture point if the skirt is subjected to lateral movement away from the container body.
 2. A package as claimed in claim 1, wherein the weakened region comprises a reduced wall section areas moulded into an interior surface of the skirt.
 3. A package as claimed in claim 2, wherein the reduced wall section areas further include at least one reduced thickness rib at a corner of the skirt.
 4. A package as claimed in claim 1, wherein the thickness of the skirt wall is 0.8 mm or less.
 5. A package as claimed in claim 4 wherein the thickness of the skirt wall is 0.5 mm or less.
 6. A package as claimed in claim 1, wherein the depth of the skirt exceeds 8 mm.
 7. A package as claimed in claim 1, wherein the base is polypropylene.
 8. A package as claimed in claim 1, wherein the container body is stepped to provide a second step that is nearer the rim than the first step.
 9. A package as claimed in claim 6, wherein at least one vertical surface of the stepped portion of the side wall displays a warning message which is only visible when the closure is removed.
 10. A package as claimed in claim 7 wherein the warning message is created by embossed or recessed letters.
 11. A package as claimed in claim 1, wherein the closure is manufactured as a co-injection using a different plastic material for the skirt. 